Characteristics and application of mullite insulating brick

Mullite insulating brick is a high alumina refractory with mullite (3Al2O3 · 2SiO2) as the main crystalline phase. Generally, the alumina content is between 65% and 75%. In addition to mullite, the minerals with lower alumina content also contain a small amount of glass phase and cristobalite; Those with higher alumina content also contain a small amount of corundum. Mullite insulating bricks can be directly used for lining of high-temperature kilns. At present, mullite insulating bricks have been widely used for lining of shuttle kilns, roller hearth kilns, glass and petrochemical kilns.

Product characteristics of mullite insulating brick:

  1. Low thermal conductivity, with good thermal insulation effect;
  2. Mullite insulating bricks have low heat melting. Due to low thermal conductivity, mullite series lightweight insulating bricks accumulate little heat energy, which has obvious energy-saving effect in intermittent operation;
  3. Low content of impurities, very low content of oxides such as alkali metal in iron box, therefore, high fire resistance; High aluminum content makes it still maintain good performance in reducing atmosphere;
  4. Mullite insulating brick has high thermal compressive strength;
  5. It has accurate appearance size, accelerates the masonry speed, reduces the use of refractory mud, ensures the strength and stability of the masonry, and thus extends the service life of the lining;
  6. Mullite insulating bricks can be processed into special shapes. To reduce the number of bricks and joints.

Classification of mullite insulating bricks:

Mullite insulating bricks are mainly divided into light and heavy mullite bricks according to the density, and 1350 mullite insulating bricks, 1450 mullite insulating bricks, 1550 mullite bricks, etc. according to the use temperature.

Performance and application of mullite insulating brick:

High fire resistance, up to 1790 ℃. The starting temperature of load softening is 1600 ~ 1700 ℃. The normal temperature compressive strength is 70 ~ 260mpa. Good thermal shock resistance. There are two kinds of sintered mullite bricks and fused mullite bricks. Sintered mullite brick is made by taking high alumina clinker as main raw material, adding a small amount of clay or raw bauxite as binder, forming and firing. Fused mullite brick is made from high alumina, industrial alumina and refractory clay, with charcoal or coke fines as reductant. After forming, it is made by reducing electrofusion method. The crystallization of fused mullite is larger than that of sintered mullite, and its thermal shock resistance is better than that of sintered products. Their high temperature properties mainly depend on the content of alumina and the uniformity of mullite phase and glass distribution. It is mainly used for hot blast stove top, blast furnace body and bottom, glass furnace regenerator, ceramic sintering kiln, dead corner lining of petroleum cracking system, etc.